Don't get too caught on up on the fact that the equations might look a little different than what you are used to. The same ideas and concepts work just like always.

(13/x) - (2/y) = - 0.3(14.6/x) - (0.4/y) = 0.04

When your variables are the denominator of fractions, it's usually going to be easier to try to add or subtract the equations together like in the post above. Just to prove the point, let's solve this one using substitution. We'll start off by solving the first equation for x. I'll put my comments in brackets.